Abstract: A Solvent extraction method for treating peri acid production wastewater is presented.The extraction is conducted by use of N_(235)as extractant and kerosene as diluent and the third phase is formed during the process.The wastewater with initial COD value over 50g/L is processed with following conditions:at ambient temperature and extractant concentration 20%,phase ratio 1:1,and extraction time 10min.After treatment the COD removal rate is up to 97% with two stages of cross current extraction.